On Friday evening, fans filled the sidewalk in front of the court and sang "Happy Birthday" while holding the plank.

Ginsburg's longtime trainer, Bryant Johnson, led the exercise. He says Ginsburg worked out Thursday night, and she told him to tell the crowd that for the first time since she underwent surgery for lung cancer in December, she has "been able to do the planks the correct way and the push-ups."

Ginsburg's son James is among those outside the court. He says the justice's plans for the evening included dinner out with family.